1. Field of the Invention
The present invention relates to a reflective liquid crystal display device or a transflective liquid crystal display device reflecting a light that is incident from an outside to display an image and a method of manufacturing the same.
2. Description of the Related Art
A development of a thin display device such as a liquid crystal display device and EL display device employing a thin film transistor (TFT) has been advancing. A liquid crystal display (LCD), which is one of flat panel displays used in place of a cathode ray tube (CRT), has the advantages of being thin and of low power consumption. For this reason, the liquid crystal display is mainly used in a notebook computer, a car navigation system, a mobile terminal device, and a television, for example. In a typical electro-optic element using liquid crystals, a liquid crystal layer is arranged between substrates having opposed electrodes with each other. A polarizing plate is formed in an outside of the substrates.
A LCD includes a transmissive LCD, a reflective LCD, and a transflective LCD or a partially reflective LCD. The transmissive LCD displays an image by transmitting light from a backlight which is a light source. The reflective LCD does not have a backlight and displays an image by reflecting the light which is incident from an outside. The transflective LCD or the partially reflective LCD uses both transmissive and reflective methods. Since the reflective LCD does not require the backlight, it is possible to reduce power consumption and to make the device thinner. Therefore, the reflective LCD has been frequently used as LCD for portable terminals. The transflective LCD, which has the advantage of both the reflective LCD and the transmissive LCD, makes it possible to prevent degradation of visibility due to the brightness difference between the light incident from the outside and the display light.
When a reflection plate of the display device of the reflective LCD is flat, background of the display device may be reflected on the display since the reflection plate functions as a mirror surface, which degrades visibility. In order to improve visibility, it is preferable to form convex parts or concave parts in the reflection plate so as to focus indirect reflected light from surrounding walls of the reflective LCD in addition to a fluorescent light and sunlight and to reflect the focused light on eyes of a user. For example, the reflection plate having the convex parts or the concave parts is formed by locally etching a metallic thin film having high reflectance ratio so as to focus the reflected light.
In the recent reflective LCD or transflective LCD, a structure of forming a reflecting electrode formed by a metal having light reflectivity on an insulating base film has been frequently used in order to improve aperture ratio or to form the convex or concave parts in the reflecting electrode which is the pixel (see Japanese Unexamined Patent Application Publication No. 2001-305515, for example). A photosensitive organic resin film, especially a photosensitive acrylic resin is often used as the insulating base film since patterning can be easily performed.
In a process of forming the reflecting electrode as above, an amine type removing liquid is used, for example, when the photoresist used for patterning the reflecting electrode is removed and cleaned. In this case, the photosensitive organic resin film which is a base film of the reflecting electrode is swelled by the amine type removing liquid. To be more specific, a gate wiring electrode, an ohmic contact film, and a source electrode and the like are formed below the photosensitive organic resin film, for example. The film thickness of the photosensitive organic resin film is different depending on places. Therefore, swelling volume of the organic resin film is different depending on the places, which leads to film floating and film peeling of the organic resin film. The film floating and film peeling of the photosensitive organic resin film is apparent in the terminal part, for example, where the reflecting electrode is not formed on the photosensitive organic resin film. Note that the terminal part is a part other than the pixel part.
A semiconductor device or the like decreasing swelling of the photosensitive organic resin film is disclosed in Japanese Unexamined Patent Application Publication Nos. 11-133627 (Nohara et al.), 2003-318402 (Muranaka), 2000-147534 (Ochi et al.). Nohara et al. discloses a method of manufacturing the semiconductor device using a resist film removing composition comprising 50 to 90% by weight of an alkanolamine having 3 or more carbon atoms, 8 to 40% by weight of a water-miscible solvent, and 2 to 30% by weight of water. Muranaka discloses a method of manufacturing a semiconductor device substrate decreasing swelling of a photosensitive organic resin film by irradiating the surface of the organic resin film with plasma. Ochi et al. discloses a display device where two layers of metal films that are reflecting electrodes formed on the organic insulation film are formed and a protective metal film formed at the lower side is etched using a reflection metal film formed at the upper side as a mask. When the resist formed on the reflection metal film is removed, the protective metal film is formed on the organic insulation film, and an amine type removing liquid is not applied on the photosensitive organic insulation film.
However, in the method of manufacturing the semiconductor device disclosed in Nohara et al., there is a need to introduce new equipment for preparing the resist film removing composition as above, which increases the cost for manufacturing the semiconductor device. Further, in the method of manufacturing the semiconductor device substrate disclosed in Muranaka, the number of manufacturing processes is increased for plasma processing. Furthermore, since new equipment for plasma irradiation needs to be introduced, the manufacturing cost increases. In the display device disclosed in Ochi et al., since two metal films need to be formed as the reflecting electrodes, the number of manufacturing processes increases and manufacturing of the display device can be complicated.